Music perception

Noteboat will be able to give you a very detailed answer - he's very knowledgeable on this sort of stuff.

Music theory is not a set of rules, which have shaped Western music, rather Western music (or, more accurately, what Western ears prefer to think of as music) has shaped music theory. It is the sum total of hundreds of years of musicians fiddling around with ideas and keeping what sounded good and throwing out what didn't.

Other cultures have different ideas of what sounds "musical" and, so, have a "different" music theory.

Some things are fixed by the laws of physics - frequencies are frequencies and sound waves cause the same response in human ears, no matter where you come from. The difference lies in how our brains perceive those sounds and is a cultural thing.

And we are also getting used to some "new" sounds: some current progressions do not sound so well two or three centuries ago. I think Noteboat wrote about it in a previous message.

Interesting. I know that there are certain aspects that come down to what we are accustomed to hearing. The tension-resolution phenomenon is particularly interesting to me, though. I know that I like songs that don't necessarily resolve but leave that hanging tension. (Probably the same aspect of my psychology that makes me like Cohen brothers movies, eh?) Nonetheless, I can still hear the "need" for the resolution. What is it about our psychology that imposes that "need?"

I promise not to start asking about the molecular biology of music next. :shock:

It's a good question. The answers are complicated, and they are actually different in different situations.

First, I'd disagree with minor chords 'resolving'. In the simplest way of categorizing sounds, there are only two types: stable sounds and unstable ones. Both major and minor chords are stable (you can end a song with them without leaving the audience hanging); dominant chords, augmented and diminished chords, and altered chords (those that include a note that must be written with an accidental in the given key, like a #5 or a b9) are unstable.

But it wasn't always so. And that brings up one problem: it's true that music theory is essentially just categorizing sounds that have already been successfully used... but it's also true that when you hear a Bach minuet, what you hear isn't what Bach heard. Over time our ideas about 'ideal' tuning have changed (several times); in Bach's day, major thirds were more 'in tune' than they are today, and minor thirds were less 'in tune'. So it was common to end a minor key piece on a major chord - that's called the Picardy third.

Greybeard is right that sounds are governed by the laws of physics. And that's one reason why we have tension in chords... When you have two notes sounding at the same time, the more often the peaks of the waves line up, the more 'consonant' we perceive the sound. Octaves have a 2:1 relationship between the waves - the upper note vibrates exactly twice for every vibration of the lower note. As a result, the octave is very consonant.

Perfect fifths vibrate in a 3:2 ratio*. Every other vibration of the lower note matches an upper note's peak. Perfect fourths are 4:3. Major thirds are 5:4. You can see that these intervals aren't bad - they line up often. For example, if you play a x02xxx power chord, the waves line up more than 50 times each second.

But a tritone is 1024:729. Now we're getting ugly... if you're playing x01xxx, the vibrations 'agree' about once every 6-1/2 seconds. That's where tension in chords comes from - those notes that don't agree. In a G7 chord you've got the notes G-B-D-F, and the B-F notes are a tritone apart.

There are also psychological aspects of sound - the field of research is called psychoacoustics. This stuff can be fascinating... it's been shown that we can 'hear' pitches that aren't actually present. When overtones line up in certain ways, some people will hear descending pitches - others hear ascending ones. We hear some sounds as louder than others - even though the sound pressures are identical. And intervals people hear as identical actually vary as the frequency range changes. Some of these effects are practically universal, others vary among groups of individuals.

My own opinion is we've muddied the waters so much we can't separate cause from effect. Physical laws are the cause of some sounds we hear; theory began around those. Then we changed things (like the tunings we use). The theory kept going on its own, building on earlier theory... which was then used to make music in the NEW tunings; then we got used to that music, used it to make more new music, which theory then analyzed... and then we changed tunings again, and so on. It's now a mish-mash of physics, history, culture, and logical extensions of prior theory.

But that's partly why it's so interesting :)

* in theory - in reality, our equal temperament adjusts the notes slightly, so these ratios aren't exact today.

That is absolutely fascinating!! The frequency matching aspect appeals to me. I think it is interesting that we are able to perceive differences such as this and convert those into an emotional response. My instructor was talking about half-steps that seem to need resolution more than others, and I would suspect that this fits in with the wave overlap idea.

It seems to be a chicken and egg problem at this point. There is clearly too much convolution of nature, theory, culture, and experience to be able to unravel all the fundamentals. I would guess that there's a really good PhD dissertation in there somewhere. 8^)

Noteboat, where do you get this endless amount of information from?? :D
are you the man who writes wikipedia as well?? :D

you never cease to amaze me when i read your posts!!

i am a science teacher and found your explanation of vibrations very interesting, it made something click thanks for that. im off to do some reading know, i am feeling very musically inferior at this point.

almann, I just get intrigued by things and start digging into them.

And I love to share how interesting this stuff is (to some of us, anyway). At out school we print a monthly newsletter for students, and I've always got a little "did you know?" article where I research odd stuff I come across. One recent one was on phonoautographs - a 19th century acoustic research tool that traced sound waves on a soot coated piece of glass. Recently some folks at Lawrence Berkeley National Laboratories reverse engineered one of these... and reproduced a singer recorded in 1860!

I'll put myself in that boat of those interested. Thanks for all the info!! And, don't stop sharing. 8^)

-Kirk

great info from noteboat.. thanks for sharing your wonderful words...